Electron discharge apparatus



United States Patent ELECTRON DISCHARGE APPARATUS John W. Campbell, In,1457 Orchard Road, Mountainside, NJ.

Filed July 9, 1956, Ser. No. 596,570

2 Claims. (Cl. 250-27) The present invention relates to electrondischarge apparatus for producing or transforming electrical wave formsor handling electrical information.

It is frequently desirable to generate electric Waves or pulses of aparticular form. Such waves may have sawtooth, square wave, stepped Waveor other types of continuous or discontinuous wave forms. In the case ofsquare or rectangular pulses and saw-tooth waves, it is often desirablethat the pulses have a very steep rise or fall. It is also frequentlydesired to obtain such pulses with an amplitude of several hundred voltsand with very precise synchronization.

It is an object of my invention to obtain all these desiderata in asimple and efiective manner. I

It is another object of my invention to provide a novel technique ofproducing electrical wave forms.

The objects of the invention are attained by connecting a pair ofelectron discharge devices to a load and controlling these devices sothat one of them supplies electrical charge carriers to the load and theother extracts charge carriers in such a manner that a desired voltagewave form is produced across the load. Simple and effective circuits forproducing these functions are provided by using electron tubes, one ofwhich is adapted to supply a secondary emission current to the load. p

. The invention will be more fully understood and other objects andadvantages thereof will become apparent from the following descriptionand the drawing in which:

Fig. l is a circuit diagram of one embodiment of my invention;

Figs. 2 to 4 are wave form diagrams illustrative of the operation of thecircuits.

Referring to the drawing, Fig. 1 shows a circuit comprising a pair ofelectron tubes T1 and T2. Tube T1 may be a pentode tube having agrounded cathode 11, a control grid 12, a screen grid 13 and asuppressor grid 14 which may be connected to the cathode. Control grid12 is preferably biased to cut 011 by a biasing source connected by alead 15 and resistor 16. A condenser 17 may bypass the bias connection15 to ground. Input signals of any desired wave form may be applied tothe electrodes of tube T1 for controlling the discharge current thereof.Such input signals may be impressed on the control grid 12 by lead 18.Screen grid 13 is maintained at a suitable positive potential, which maybe of the order of several hundred volts, by a lead 19 to a source of13+ voltage. It will be understood that all voltage sources and signalsources may be returned to ground. The anode 20 of tube T1 is connectedto terminal P of any desired load. If, for example, the circuit is usedas a saw-tooth wave generator, the load may be the electrostaticdeflection plates of a cathode ray tube. In this case the load will besubstantially capacitive as indicated by the condenser 21.

Tube T2 includes a grounded cathode and a control grid 26 connectedthrough a resistor 27 to a source of biasing potential at terminal 28.The biasing source may be bypassed to ground by condenser 29. A screengrid 30 has a connection 31 to a suitable source of positive voltage. Asuppressor grid 32 is connected to the cathode but, if desired, thesuppressor grid may be omitted. In the path of the electron stream thereis a secondary electron emitting anode or dynode 35 connected toterminal P of the load. Dynode 35 may be formed of such a material ormay be coated so as to enhance its electron emission when bombarded byhigh velocity electrons. The anode 36 is maintained at a suitable 13-!-Voltage, the other side of the B+ source being returned to ground or thecathode in the usual manner. The discharge current in tube T2 iscontrolled by input signals supplied by lead 37 to one of the electrodesthereof, for example, control grid 26.

The operation of the circuit illustrated in Fig. 1 may be explained withreference to Figs. 2, 3 and 4. Referring to Fig. 2, let it be assumedthat tubes T1 and T2 are cut off when the bias isbelow the valuesindicated by dotted lines 41 and 42, respectively. The actual biasessupplied to tubes T1, T2 through leads 15 and 28, may be more negativethan the cut oif biases 41 and 42, as indi# cated by the lines 43 and44. Tubes T1 and T2 will then be normally biased to cut off. Inputcircuits 18 and 37 supply pulses 45 and 46 to tubes T1 and T2 in thetime sequence indicated in Fig. 2. The first pulse 46 will render tubeT2 conductive and cause a stream of high velocity electrons to strikedynode 35. The voltages applied to screen grid 30 and anode 36 willcause each electron striking dynode 35 to produce a plurality ofsecondary electrons and the secondary electrons will be attracted toanode 36. .Suppressor grid 32, if used, is helpful in preventingsecondary electrons from being attracted by screen grid 30. Hence pulse46 will cause a large current to flow from point P through dynode 35 toanode 36 and thence through the B+ source to ground. This current willcause the voltage across load 21 to rise rapidly, as indicated by line47, to a positive value 48. The voltage across the load will remainsubstantially constant until the first pulse 45 .of Fig. 2 is appliedtocontrol grid 12 of tube T1. As pulse 45 rises above the cut off value 41of tube T1, a largeelectron current will flow to anode 20 and terminal'Iso that the voltage across the load Will fall as indicated by line 49 toa value 50. Upon termination of pulse 45, the voltage across load 21will remain at value 50 until the next pulse 46 is applied to tube T2,whereupon the second rectangular wave 51 will be produced in the samemanner as the preceding wave. The zero voltage line for the load isindicated by line 52.

The manner in which the circuit of Fig. 1 may be openated to generatesaw-tooth waves will be explained with reference to "Fig. 3. Dashedlines 55, 56 indicate the values of the bias at which tubes I 1 and T2respectively, will be out 01f. Assume that the input signal applied tocontrol grid 12 of tube T1 is a steady potential 57 slightly morepositive than the cut off bias of that tube, so that tube T1 will have asteady small discharge current. Assume that the bias applied to tube T2is as indicated by line 58, that is, that it has a value such as tomaintain tube T2 biased below cut off. When a positive pulse 59 isapplied to control grid of tube T2 so as to drive it out of cut-011,high velocity electrons will strike dynode 35. Current multiplicationwill occur at dynode 35 to cause a large momentary current to flow fromloads 21 through dynode 35, anode 36, the B+ voltage source connected tothe latter and then to ground. This action will cause a steep rise inthe voltage across load 21, as indicated by the line 60. Upon thetermination of pulse 59, tube T2 will be cut otf. Tube T1, however, isconducting and by virtue of its being a pentode, supplies electrons toterminal P at a nearly constant rate so that the voltage across load 21falls steadily as indicated by the Patented Sept. 27, 1960 line 61. Thisaction will continue until the second pulse 59 occurs and causes tube T2to conduct again and suddenly raise the voltage to the maximum value. Itis clear therefore that the voltage across load 21 will have thesaw-tooth'form indicated by lines'6t "61.

Still another manner of operating the circuit of Fig. l is illustratedin Fig. 4. Here, again,let it be assumed that tubes T1 and T2 arenormally biased below cut off and that pnlses 65 are applied to tube T2and ipulses 66 are applied to tube T1. Pulses 65 cause conduction intube T2. Electrons thus flow from terminal P to the dynode 35 andproduce series of rises 67, 68, 69 in the voltage across load 21. Afterthe last pulse 65, the voltage across the load remains at the value 70until'pulses 66 are applied to tube T1. Each of the latter pulses causesa stream of electrons to flow to terminal P and produces a sharp drop71, 72 and 73 in the voltage across load 21. The load voltage thenremains at the value 74 until the next series of pulses 65 is applied totube T2, whereupon a second stepped voltage wave Will'be generated.Figs. 2, 3 and 4 are to be considered merely illustrative of the manyWays the circuit may be operated to generate a desired wave form.

It will be understood that the circuit herein illustrated is anexemplary embodiment of my invention, which lends itself to a greatvariety of applications. Various modifications of the embodiment of theinvention herein illustrated will be evident to those skilled in theart. Therefore I do not Wish the invention to be construed as limitedexpect as defined in the following claims.

I claim:

1. An electron discharge circuit comprising a load, an electron tubehaving its anode connected directly to one side of said load and acathode connected directly to the other side of said load, a controlelectrode in said tube, means for biasing said control electrodesubstantially to cut off and means for applying potentials to said tubefor producing discharge current therethrough, a second electron tubeincluding a secondary electron emitting electrode connected directly tothe anode of said first tube and a cathode connected to the said otherside of the load, means including an accelerating electrode in saidsecond tube for causing the electrons leaving the cathode thereof tostrike the secondary electron emitting electrode with a sufficientvelocity to produce the current multiplication thereat, means includingan anode juxtaposed to said secondary emitting electrode for collectingthe secondary electrons emitted therefrom and means including thecontrol electrode-of said second electron tube for biasing said secondtube to cut off and for applying input potentials for causing dischargecurrent through said second tube alternately with said first tube and anoutput lead connected to said onesideof the load.

2. A saw-tooth .Wave producing circuit comprising a ncnoscillatory'load, a pentode electron tube having its anode connected directly t'ooneside of said load and its cathode connected directly to the-otherside of said load,

7 means for applying potentials to said tube forproducing a steadydischarge current therethrough, a second electron tube including-asecondaryelectron emitting electrode connected directly to the anode ofsaid first tube and a cathode connected to the said other side of theload, means including an accelerating electrode in said second tube forcausing the electrons leaving the cathode thereof to strikethe'secondaryemitting-electrode witha'sufficient Velocity to produce acurrent multiplication thereat, means including an anode juxtaposed tosaid secondary emitting electrode for collecting the secondary electronsemitted therefrom and means including the control electrode of saidsecond electron tube-for biasing said second tube to cut oil? and forapplying positive voltage pulses to said control electrode for causingdischarge currents through said second tube and an output lead connecteddirectly to said'one side of said load.

References Cited in the file of this patent UNITED STATES PATENTS2,299,252 Pierce Oct. 20, 1942 2,438,586 Sziklai Mar. 30, 1948 2,456,754'Szil ali Dec. 21, 1948 2,487,603 Scoles Nov. 8, 1949 2,519,030 -DomeAug. 15, 1950 2,567,247 Spalding Sept. 11, 1951 2,602,889 Post July 8,1952 2,871,378 Lohman Ian. 27, 1959 OTHER REFERENCES Emitter-CoupledDiiferential Amplifier, by D. W. Slaughter, I.R.E. Transactions, March1956, pp. 51-53 inclusive.

I; uni-a.

